Lumiera Design Documents

Lumiera is to be a professional tool for video editing on
GNU/Linux systems. The vision of the development team defines a modern design
for the core of a Non-Linear Editing software. A key aspect of Lumiera
is the strong separation between the user interface and the processing core.
We are developing Lumiera with a GTK GUI but that will in no way be exclusive;
other GUIs can be written, as well as scripts to drive the core.
This becomes possible by an ongoing effort to decrease coupling. Each major
component in the application strives to be open to extensions, but closed
against external modification. The presentation, the model and the “performing”
of the model are separate and self-contained parts of the application. Lumiera
as a processing core will be able to perform any conceivable
task on video and audio, maybe even tasks entirely unrelated to video editing.

Workflow

The word “workflow” is used to name the way tasks can be achieved in an
application. Any operation in Lumiera must be possible in the most suitable and
stringent fashion. The workflow is closely related to how flexible the GUI is
but is also the concern of deeper and more technical parts of the application.

Overview

Lumiera is built from numerous subsystems.
This overview will provide a general description of the major components
from the highest to the lowest level.
Lumiera is composed of three main areas with a few additional extra components.
We discuss these areas below.

Stage: Graphical User Interface

User interfaces are implemented as plug-ins. As a consequence, it is
possible to interface with Lumiera through scripts. It is also possible to create
specialised GUIs. The interface is the component that is closest to the user. It
provides purely visual interaction with the user. Within this work environment, the user
manipulates, organizes, loads, configures all sorts of data, especially MObjects (media
objects) and Assets. These elements are contained within a structure called the Session.
→ GUI/Stage-Layer design documents

Steam: the Transformation Layer

The “Steam Layer” covers several closely related aspects.
When the user works with the GUI, all the clips, effects and other visually presented
components are actually stored within the Session model (“high-level model”). Any editing
operation initiated by the user is actually executed in the context of the session. Next,
after each change, a component known as the Builder assembles the contents of this session model
to transform them into a network of nodes, which can be efficiently performed for rendering.
Often, we refer to this node structure as the “low-level model”. On rendering or
playback, the Steam-layer is responsible for accessing this low-level node structure to
generate individual frame render jobs, ready to be handed over to the Vault, which
finally initiates the actual rendering calculations.
→ more about the Model
→ design of the Engine subsystem

Vault: Low-Level Services

The Vault Layer attaches to the low-level model and the render jobs generated by the Steam Layer.
It actually conducts the rendering operations and makes heavy use of the
Input/Output System for accessing media content and sending generated data to
the screen or to external output.
→ Lumiera Vault design level documents
→ technical documentation

Extra Components

The Application

The application controls the initialization and shutdown procedures as well as
loading external elements such as plug-ins, which are widely used throughout
Lumiera. It acts as the framework which supports core component operations. This
framework is complemented by a library of commonly used components, algorithms and data structures.
→ Application framework

Plug-ins play an important role within Lumiera since the application relies
heavily on current FLOSS implementations and external libraries. Moreover, the
application will be configurable and can be extended in various
ways; whenever some extension isn’t permanent or will be used only on demand, it
is packaged as a separate module into a plug-in. For example, the GUI of Lumiera
is a plugin.
→ design documents regarding the Plugins